Wiring used in aerospace applications must meet rigorous performance criteria, including durability, wear resistance, chemical resistance, arc resistance, and resistance to fluid ingress, and these criteria must be met both at ambient temperature and at elevated temperatures, e.g., 150-200° C. Failure of any of these criteria in flight could be catastrophic, leading to property damage and/or loss of life. Other beneficial properties for wiring used in aerospace applications include markability, good conductivity, and light weight. The coatings used on the conductor portions of the wires can have a significant effect on the performance of the wire according to all these criteria.
Existing aerospace wiring suffers from several drawbacks. For example, wires with extruded ETFE coatings may provide insufficient resistance to abrasion and cut through, particularly at elevated temperatures. As another example, wires coated with a composite tape wrap (e.g., polyimide alone or with a PTFE layer) often fail to provide sufficient sealing due to seams inherent in wrapping the tape. The use of an additional PTFE layer also can result in tearing during installation and reduced markability. Further, such composite tapes must be heated to improve sealing during installation, and this heating is performed at elevated temperatures that preclude the use of certain conductor materials that may be damaged by such temperatures (e.g., a tin-coated conductor). Additional drawbacks and advantages of existing aerospace wires and manufacturing methods are recognized by those skilled in the art.
The present disclosure seeks to overcome certain of these limitations and other drawbacks of existing aerospace wires and manufacturing methods, and to provide new features not heretofore available.